Cellular wireless communication devices (WCDs), such as a mobile phones and personal digital assistants, have become increasingly common in recent years. In general, a WCD communicates over an air interface with a wireless carrier's network, which provides the device with access to other network resources, such as a communication channel to interact with other devices or with network servers.
In a typical wireless carrier network, multiple base stations are positioned throughout a market area, and each base station radiates to define a cell and, in turn, cell sectors, in which WCDs can operate. Air interface communication between a given base station and a WCD may operate in accordance with various air interface protocols, well known examples of which include CDMA (e.g., 1xRTT, 1xEV-DO), iDEN, TDMA, AMPS, GSM, GPRS, UMTS, EDGE, and WiMAX (e.g., IEEE 802.16), among others. One or more base stations are then typically coupled or integrated with a base station controller, which manages air interface operation such as use of air interface channels and handoff of devices between sectors. In turn, one or more base station controllers may be coupled with a switch (e.g., mobile switching center) or gateway (e.g., packet data serving node) that provides connectivity with a transport network such as the public switched telephone network (PSTN) or the Internet. Within this arrangement, a WCD may communicate via a base station, base station controller, and the switch or gateway, with entities on the transport network.
As wireless communication technologies advance, new forms of air-interface communication are developed, and wireless carriers may seek to upgrade or expand their networks to offer the latest technologies to subscribers. Because this upgrade or expansion is usually a gradual process, wireless carriers may operate multiple networks simultaneously for some period of time, with each network employing a different air interface communication technology. In this respect, the access networks may be overlaid upon one another, and may serve WCDs operating in substantially the same market area. As an example, a wireless carrier may operate both a 3G network (e.g., CDMA) and a 4G network (e.g., WiMAX) simultaneously in the same market area for some period of time. During this time, the wireless carrier may then offer their subscribers dual-mode WCDs that are capable of operating in each of the networks.
An important feature of contemporary cellular wireless carrier networks is an ability to locate the geographical position of a WCD. Such a feature was initially developed to assist emergency services in locating a WCD. However, the availability of location information to support E911 services has given rise to the development of many other location-based service (LBS) applications as well. For example, given the location of a WCD, an LBS provider (e.g., a wireless cellular carrier or third party) can provide the WCD's user with information related to that location, such as a weather or traffic report, a list of services or establishments (e.g., restaurants, parks, or theatres), and/or a map of the user's location with directions for travel between the user's location and another location. Many other examples are possible as well.
In practice, when a requesting entity wants to determine the location of a WCD, the entity may send a location request to the wireless carrier that serves the WCD. In one example, the location request may be a “low precision request” that seeks a low precision indication of the WCD's location, such as an indication of the location of the cell/sector in which the WCD is currently located (e.g., the geographic location of the cell/sector's centroid). As another example, the location request may be a “high precision request” that seeks a high precision indication of the WCD's location, such as a more precise indication of the geographic position of the WCD itself (e.g., a geographic location determined using satellite-based positioning data). In this respect, a low precision indication of the WCD's location may be used in determining the high precision indication of the WCD's location. Further, if the determination of a high precision indication of the WCD's location fails, the low precision indication of the WCD's location may be used as a fall back option.
As can be seen, the ability to determine a low precision indication of the WCD's location plays an important role in location determination. Accordingly, an improved location method for determining an accurate low precision indication of a WCD's location is desirable.